The present invention relates generally to spacecraft, and more particularly, to a three-antenna storage and deployment system for use on a spacecraft.
The assignee of the present invention manufactures and deploys communication spacecraft. Such spacecraft have antennas stowed thereon that are deployed once the spacecraft is in orbit. The antennas are used for communication purposes.
A number of deployable antennas have been developed in the past. Many of these antennas are used in ground-based vehicular applications. For instance, the Winegard Company has patented a variety of deployable antennas that are primarily designed for use on recreational vehicles, and the like. These patents include U.S. Pat. Nos. 5,554,998, 5,528,250, 5,515,065, 5,418,542, 5,337,062, and 4,771,293. The antennas disclosed in these patents have a single main reflector that illuminates a feed horn. These antennas are primarily designed to receive television signals broadcast from a satellite.
U.S. Pat. No. 4,771,293 entitled xe2x80x9cDual Reflector folding Antennaxe2x80x9d discloses a folding antenna for use in a satellite communication system that is used as part of a mobile earth station that is part of a satellite communication system for news gathering purposes. This antenna has a supporting base, a main reflector and a subreflector. The main reflector and subreflector rotate downward toward the base from a deployed position to a stowed position where the two reflectors lie relatively close to the base. The base forms part of a container that encloses the reflectors when in the stowed position. The two reflectors are hinged relative to each other and relative to the base. The two reflectors move from a stowed position where they lie relatively close to the base, to a deployed position where they are relatively spaced from the base.
U.S. Pat. No. 5,554,998 entitled xe2x80x9cDeployable satellite antenna for use on vehiclesxe2x80x9d is typical of the other cited patents and discloses a deployable satellite antenna system that is intended for mounting on the roof of a vehicle. The elevational position of the reflector is controlled by a reflector support having a lower portion pivotably attached to a base mounted to the vehicle. The elevational position of the reflector can be adjusted between a stowed position in which the reflector is stored face-up adjacent to the vehicle and a deployed position. The feed horn is supported at the distal end of a feed arm having a first segment attached to the reflector support extending outward between the base and reflector, and a second segment pivotably connected to the distal end of the first segment. The feed horn segments move between an extended position in which the feed horn is positioned to receive signals reflected from the reflector, and a folded position in which the feed horn is positioned adjacent to the reflector. A linkage extends between the base and the second segment of the feed arm causing the second segment of the feed arm to automatically pivot to its folded position when the reflector is moved to its stowed position. The linkage also allows a spring to pivot the second segment to its extended position when the reflector is moved to its deployed position. The azimuth of the antenna can be controlled by rotating the base relative to the roof of the vehicle.
The other cited patents generally relate to deployable satellite antennas that have all the major antenna components (i.e. feed horn assembly, subreflector, main reflector) move independently to deploy and stow the antenna. These other patents are generally unrelated to the present invention.
None of the above-cited antennas are particularly well-suited for use on a spacecraft. Single reflector antennas are typically not used in spacecraft communication systems. The dual reflector antennas disclosed in U.S. Pat. No. 4.771,293, as well as the other antennas, have many moving parts and would therefore be relatively unreliable when used in space applications.
U.S. patent application Ser. No. 69/663,544, filed Sep. 15/2000, entitled xe2x80x9cMain Reflector and Subreflector Deployment and Stowage Systemsxe2x80x9d assigned to the assignee of the present invention discloses improved systems that are used to store and deploy an antenna disposed on a spacecraft. The antenna comprises an RF teed horn assembly, a main reflector assembly and a subreflector. Alternative embodiments of this invention package one or two antenna systems each having an RF feed horn assembly, a main reflector assembly and a subreflector.
Heretofore, there have been no systems that are used to store and deploy three reflector antennas that are located on the same side of a spacecraft. It would be desirable to have a system that has the ability to store and deploy three antennas on the same side of a spacecraft. Therefore, it is an objective of the present invention to provide for a three-antenna storage and deployment system for use on a spacecraft.
To accomplish the above and other objectives, the present invention provides for an improved antenna deployment system that is used to store and deploy three reflector antennas that are located on the same side of a spacecraft. The three antennas are nested and are stacked in a stowed condition and are individually and sequentially deployed into their respective deployed positions. One or more feed horns are attached to the spacecraft that illuminate the respective antennas.
One dual axis deployment mechanism is used to deploy each antenna. The respective dual axis deployment mechanisms are used to both deploy the antenna and steer the beam produced by the antenna (beam steering). The dual axis deployment mechanism comprises a dual-axis rotatable hinge structure affixed to the spacecraft that is coupled to the antenna by way of a substantially rigid reflector support structure. The dual axis deployment mechanism is actuated and controlled to deploy the antenna and steer the antenna beam.
The substantially rigid reflector support structure is attached to a first portion of the dual-axis rotatable hinge structure that rotates about a first axis. The second portion of the dual-axis rotatable hinge structure is coupled to the spacecraft and rotates about a second axis. This provides for dual-axis rotation of the deployed antenna.
Each antenna is disposed in a fixed relation relative to the one or more feed horns when the antenna is in the deployed position so that it generates a predetermined beam coverage pattern. The predetermined beam coverage pattern is steerable by actuating the dual-axis rotatable hinge structure to rotate the antenna about either of the axes.
The present invention provides compact packaging of three antennas, and thus provides for an antenna system having a compact stowage volume. The present invention stows and deploys the three antennas as a single unit.